US1578020A

US1578020A - Method of drying and handling wood veneer

Info

Publication number: US1578020A
Application number: US516528A
Authority: US
Inventors: Elmendorf Armin
Original assignee: Individual
Current assignee: Individual
Priority date: 1921-11-21
Filing date: 1921-11-21
Publication date: 1926-03-23
Anticipated expiration: 1943-03-23

Description

March 23 1926.

A. ELMENDORF METHOD 0F DRYNG AND vHANDLING WOOD VENEER Filed Newa 2.1. 1921 MO/src/RE CONTE/v7' Patented Mar. 23, 1926. i

UNITED STATES A l 1,518,020 PATENT OFFICE.

ARMIN ELMENDORF, OF CHICAGO, ILLINOIS.

METHOD OF DRYING AND HANDLING WOOD VENEEB.

Application led November 21, 1921. SerialI No. 516,528.

To all whom it may concern.'

Be it known that I, ARMIN ELMENDORF, a citizen of the United States, residing at Chicago, county of Cook, State of Illinois, have invented a certain new and useful Improvement in Methods of Drying and Handling Wood Veneer, and declare the following to be a full, clear, and exact description of the same, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying.drawings, which form a part of this specification.

The common method of handling wood veneer 1s to cut or tear 1t lnto sheets as 1t 1s formed from the log, the sheets being then dried and reaching the consumer in what should be a l'lat dry state. There 'are several' common methods of drying, namely between hot plates,between rolls in a heated chamber, and in kilns. It is very seldom that a sheet of veneer emerges from the drying rocess without beine` war ed and cracked.'

and transporting them, furtherbreaking or cracking thereof, particularly along the edges, invariably occurs. Therefore when the veneer reaches the consumer who is to work it up into finished products, it is in the form of more or less warped and cracked sheets which must be flattened and trimmed, the trimming alone often resulting in a great waste of material due to the fact that a large percentage of the stock must sometimes be cut away to remove portions unfit for use.

The object of the present invention is to produce a simple, novel and economical method of handling and drying veneer, so that the veneer will reach the consumer in a sound unwarped condition and there will be a minimum waste of material from the time the veneer is fashioned from the log to the time it is cut up by the consumer.`

When veneer is cut from the log it is in a wet state, that is a state in which the moisture content is above what is known as the liber saturation point. As long as the moisvture content remains above thesaturation point there is substantially no expansion or contraction of the veneer as the amount of moisture increases or decreases. As soon as the moisture content drops below the saturation point, in the drying of the veneer, contraction across the grain begins. Similarly for any increase or decrease in the moisture content, as long as the total remains below the saturation point, there is a correspondlng expanslon or contraction of the veneer.

In the ordinary methods of handling veneer,

it is dried sufficiently, in the course of manufacture, to reduce moisture content below the saturation point, thus permitting cracking and warping to take place and leaving the sheets in a comparatively fragile condition which causes them to break and crack still more during' subsequent transportation and handling.

In accordance with my invention the veneer is not out or broken into sheets as it is formed, but is rolled up so that if desired, Iall of the veneer obtained from a log may be in a single long sheet. I then drythe sheet by carrying it through a suitable drying'chamber in which the heat, humidity.

and convection factors are properly coordinated effectually to dry the veneer, without` danger of checking the surface, until the moisture content has dropped toa point in the vicinity of the saturation point. This first drying step does not result in any apreciable contraction of the veneer but, a er the saturation point has'been passed in the downward direction, further drying is accompanied by a contraction of the veneer. The second stage of the drying is accomplished While the veneer is being held together in such a manner that it cannot be split although retaining its natural liexibility. The most. convenient Way to hold the veneer together and prevent it from splitting is to attach adhesive tapes to the same when, in its travel, it reaches a. point where the moisture content is in the vicinity of the saturation point. The adhesive tape is preferably made of cloth or other strong flexible material and, while the veneer is shrinking in thei direction of the length of the tapes during the second stage of the drying process, the tapes do not shrink but compensate for the shortening-of the veneer by Wrinkling. This Wrinkling of the'tapes o f course loosens them and, if left loose, would make them useless. I therefore press down the'wrinkles as they are formed so that the tapes are in effect progressively shortened by a wrlnkling operation and kept cemented to the veneer notwithstandingsuch wrin- 'kling. VThe tapes, even in their wrinkled conditions, therefore possess tensile strength in the direction `of their lengths and serve effectively to tie or bind the fibers together and prevent cracking or splitting. The drying operation is preferably continuous, the sheet of veneer being progressively unrolled, dried, and again' rolledup with the tapes fastened thereto. During the drying process the veneer is fed transversely to the grain and over guides whose axes are parallel with the grain, the guides being preferably so disposed that the veneer is bent first in one direction and then in the other to make a series of transverse corrugationse thereby insuring that the drying will be accomplished while a line drawn transversely of the sheet at any point remains a straight line which ultimately becomes an element of a cylinder when the veneer is rolled up after the drying operation.

The'dried and taped roll-bf veneer may vbe transported and handled in that form, no

division of the material into strips or panels being done until the veneer reaches the` user. When the veneer reaches the user it is Hat along transverse lines and may read-y ily be iattened out in the lengthwise direction. Since there is no splitting or cracking of the veneer in drying, there will be little need for cutting away stock along the edges in order to remove unsoundfportions.

The various features of. novelty whereby my invention is characterized will herein` after be pointed out' with particularity in l lowing the 2claimsybut, for a full understanding of my invention and'of its objectsy and.ad vantages reference may be had to the fol-` detailed description taken in' connection with the accompanying drawing, wherein: i Y

Figure'l. is a diagram showing va typical expansion and con-traction curve for wood based on .variation in Amoisture content;

Fig. 2 is a side elevation, with the nearl wall removed,'of an apparatus in which my vinvention may conveniently be carried out;

Fig. 3 is a section taken approximately Online d---l of Fig. 2; andV Fig. 4 is a section taken approximately on line 4 4 of Fig. 2. y

A Referring to the drawing, A represents a Aroll of wet veneer which is adapted to be supported in suitable bearings l outside of and near the top of a vertically-elongated chamber 2. In the chamber 2 are a series of light rollsv 3 of comparativelylarge diameter, the lowermost roll being at the bottom of the chamber and being supported so as to be held against movements other than rotary movements. The lower roll may be driven element co-operating with a gear wheel or,

sprocket wheel 4 mounted on the roll. The remaining rolls of the series rest one upon the other, their journals 5 projecting into slots or ways formed between pairs of vertical guides 6 arranged at opposite ends of the rolls. This arrangement permits the rolls to rotate freely in contact with each other and to adjust themselves in the vertical di-A rection. Behind the uppermost roll and every other roll of the series are arranged guide fingers 7 while in front of the remaining rolls of the series are similar guide fingers 8. The fingers are so proportioned that when the sheet of veneer a is passed into the top of the chamber 2 through a slot or opening 9, it will move across the top of the uppermost roll and then be` deflected downwardly around the roll andf forwardly across the top of the second roll where it engages with the guide fingers 8 in front of the sec- 0nd' roll and is carried down around the front of the second roll and underneath the latter. In this way when the veneer is fed into the apparatus, it will be positively guided in position between each pair of rolls and, by the time it reaches the bottom of the chamber, it has taken on a sinuous or deeply.

waved form.. However, the curvatures are all in one direction, all lines extending transversely of the sheet being kept straight. Furthermore, as any section of the sheet passes along the series of rolls it is first bent in one direction and then in the opposite direction so that there is no tendency to give it a permanent curvature.

When the lowermost roll of the series is driven, all of the other rolls are set in motion, each roll forming with the next one above it a friction drive. This relation between the rolls is not disturbed by the presence of the veneer between them because each section of veneer'acts as thoughit were a part of the lowermost roll along the line of contact between two rolls. As the lowermost roll is driven, the entire seriesfis setin rotation andthe veneer lis advanced-downwardly ythrough the chamber.` Within the chamber are steam coils 10. At the top of the chamber is an outlet flue 11 controlled by a damper 12. Within the chamber are fans 13 at opposite ends of the rollers, although only one such fan is illustrated in Fig. 2. As the veneer passes down through the chamber, itis gradually dried, the vari-v ous factors entering into the drying process `one end of the latter.

chamber the veneer moves free from tension because there is no shrinking of the veneer on account of the loss of moisture until the vicinity of the saturation point has been reached. Therefore there is no dangerf tearingl the veneer.

The upright chamber 2 communicates with the top of a horizontal chamber 14 at In this horizontal chamber are a. series of rolls 15 spaced apart from each other and arranged in staggered 'relation to each other; half of the rolls being conveniently placed at one `elevation and alternate rolls at a lower elevation. Suitable guides 16 are associated with the rolls 15 so that after the veneer has been directed by a suitable guide 17 from the lowermost roll 3 to the first of the rolls 15, the guides 16 will insure that the veneer will be properly guided past thc series of rolls 15 by which it will be given a sinuous or wave-like configuration; but, being alternately waved in one direction and then the other as it passes through the lower chamber sothat there will be no tendency to cause it to set permanently in curves or waves. After passing through the horizontal chamber, the veneer is wound on a roll B beyond the end of the chamber; this roll being preferably driven by a suitable driving mechanism 18 which does not positively drive the roll of veneer but permits slippage to occur; suchdrive mechanisms being commonly used 'in paper making.

In the bottom of the chamber 14 are steam pipes 20 and the chamber is also provided with fans 21, arranged at opposite ends of the rolls 15. The factors that determine the extent of drying of the veneer in this chamber are so regulated that the drying is carried to any`desired point be-lowthe fiber saturation point. The drying of the veneer in the horizontal chamber is accompanied by a contraction or shrinking of the veneer transversely of the grain, that is in the di'- rection of travel of the sheet. It is for this reason that the rolls over which it passes in this chamber are spaced apart from each other, tlius avoiding the tearingof the material. The vveneer cannot vbe positively driven by the rolls through the horizontal chamber as it is through the upright cham-l ber but it is most conveniently pulled along from the end which is being wound on the roll B. EvenV the slight pull required to draw the veneer through the horizontal chamber might cause the veneer to tear' and splitting or cracking of the veneer in this chamber might also result from other causes. In order to prevent the tearing of the veneer Neither by the pull on the same while it is going through the horizontal chamber or from other causes, I apply to at least onev face of the veneer one or morel tapes whichV are fed against the veneer when it reaches the bottom of the upright chamber, namely the point where a condition of approximate fiber saturation exists. Two such tapes, one along each edge, are preferably applied. One of these tapes is shown in Fig. 2, the same being wound on a roll C lying in front of a Slot 22 in the wall of the upright chamber at about the level of the top of the lowermost roll 3. The tape o is carried from the roll C through an apparatus 23 for applying glue or moisture, as the case may be. The tape is thencarried vforward between the two lowermost rolls 3 and is pressed by the same into contact with the veneer; these two rolls serving also as the feed rolls for drawingv in the tape. i

As the taped veneer passes onward through the horizontal chamber, the veneer shrinks or contracts but the tape does not and, in order to permit the tape to serve its intended purpose it must be pressed down and the wrinkles therein flattened as wrinkles are formed during the shortening of the tape.- -This may conveniently be accomplished by.

so placedthat as the vencer passes between a roll 15 and the corresponding pressure device, the members 25 and 2 6 engage the tape and press it Hat, In this way, as the veneer shrinks, the tapes are alternately wrinkled and pressed so that they will serve elfectually to bind the veneer against splitting or crack- 1ng and will also give mechanical strength to the veneer to permit the same to be drawn through the lower chamber without danger of tearing the same. I f

I prefer to employ a higher temperature in the upright chamber than in the lower chamber,- the temperature in the upright chamber being preferably somewhat. above the boiling point of water and the temperature in the lower chamber being preferably below the boiling point of water.- The fans circulate the gaseous atmosphere within .the

lchambers, thus permitting rapid drying to beefected by reason of the passage of currents of air across the surface of the veneer. The humidity lin each of the chambers may be controlled by varying thef amount of air that is drawn into the system in proportion to the amount of air and watery vapor that is (permitted to flow out through th'e flue, an by varying the pressure of the steam in the heating coils so as toxvary the temperature. Consequently the three factors.con

sisting of heat, humidity and convection may all beregulated so as to produce rapid fir-ying Withoutinducing splitting or checki ing. y It will therefore be seenthat the veneer will be rapidly dried and, since it is bent first in one direction and then in the other as it travels through the drying chambers, any tendency to Warp is entirely overcome and when the veneer is dry and Wound up in the form of a roll as a finished product, all transverse lines will be straight, that is elements of the cylindrical shape Which the veneer takes when rolled up.

If desired, each ofthe rolls l5 may be provided with a shaft 27 extending out through one side of the chamber 14 and provided with a squared end 28. A Wrench may be applied to the squared end of one shaft after the other in the series of rollsin the horizontal chamber so as to draw the advanfing free end of a piece of veneer through the horizontal chamber and bring it in position to be engaged with the roll on which it is to be Wound up.

I claim:

1. The method of treating veneer which consists in drying it until the moisture content is in the vicinity of the fiber saturation point, applying adhesive tape to the veneer transversely of the grain, and then further 'drying the veneer.

2. The method of treating veneer which consists in drying it until the moisture content is in the vicinity of the liber saturation point, applying adhesive tape to the veneer transversely of the grain, then further drying the veneer, and pressing the tape against the veneer and iattening the same as wrinkles are produced in the tape by reason of the shrinking of the veneer.

3. The method of treating veneer which consists in partially drying it While bending it alternately in opposite directionsparallel to the fibres so as to maintain them straight` applying-adhesive tape to the veneer across the grain, and then further dryingthe veneer.

4. The method of treating veneer which consists in partially drying it while bending it alternately in opposite directions parallel to the fibres to maintain them straight, applying adhesive tape to the veneer across the grain, further drying the veneer and at the same time bending it alternately in opposite directions so as to malntain lines running across the same 1n the dlrection of the gram straight.

5. The method of treating veneer ivhich consists in partially drying it while bending it alternately in opposite directions paralle l to the libres to keep them straight, applying-'adhesive tape to the veneer across the grain, further drying the 4veneer and at the same time bending it alternately in opposite maining rolls of the series to be frictionallyl driven, and` passing heated air over the veneer While it is passing through the rolls.

7. The method of treating veneer which consists in applying adhesive tape to the veneer transversely of the grain and While the veneer still contains moisture to be re'- moved, and then 'drying the Veneer to remove such moisture.

8. The method of treating veneer which consists in drying it until the moisture content is in the vicinity of the fiber saturation point, cementing to the veneer a member to reinforce it transversely of the grain, and then. further drying the veneer.

9.'Tl1e method of treating veneer which consists in drying it until the moisture content is in the vicinity of the fiber saturation point, applying adhesive tape to the veneer transversely of the grain along the two edges, and then further drying the veneer.

10. The method of drying veneer which consists in passing it over a series of rolls arranged to cause the veneer to assume a sinuous shape along lines transverse to the ibers in the veneer, While in contact with the rolls and applying heat to the veneer during its passage over the rolls.

11. The method of drying veneer which consists in bending it alternately in opposite directions parallel to the fibres to keep the ibres straight, and simultaneously applyingheat to the veneer.

12. The method'of treating veneer which consists in drying it and, during the drying process, applying reinforcing strips to the surface of the veneer transversely of the grain. l y

13. The method of treating veneer which consists in drying it slowly and, during .the

drying operation, gluing reinforcing strips i tion.

ARMIN ELMENDORF.